1. Field of the Invention
The present invention relates to a welding positioning system for lapping a welding part of a metal plate for seam welding, and more particularly to a welding positioning system for seam welding, the system adapted to maintain a lapped portion of the metal plate at a constant level and to expedite a positioning decision of a panel, thereby shortening working hours.
2. Description of the Prior Art
Generally, a seam welding is a kind of electric resistance welding primarily used for seam welding of a metal plate, where, welding parts of the metal plate are lapped into which a pair of rollers comprising electrodes are inserted, allowing the lapped welding parts to be welded by rotation of the rollers.
The welded parts of the metal plate thus welded by the seam welding are determined in welding positions thereof by a welding positioning system, and lapped portions thereof are also determined at this time. Positions and lapped portion of the welding parts greatly influence the quality of the welding.
FIGS. 1, 2 and 3 are schematic drawings for illustrating methods for determining the positions of welding by way of the welding positioning system according to the prior art.
The welding positioning system includes left and right clamps 2 and 4 for vertical movement, left and right stoppers 6 and 8 slidably inserted into the left and right clamps 2 and 4 and left and right cylinders 10 and 12 for actuating left and right stoppers 6 and 8.
As illustrated in FIG. 1, the stopper 6 is advanced by actuation of the left cylinder 10 in a state where the left clamp 2 is lowered. At this time, advanced distance of the left stopper 6 is adjusted by adjustment of an adjuster 14 mounted at a rear side of the left cylinder 10. Successively, the right clamp 4 is raised to insert a right metal plate 18 downward of the raised right clamp 4. The right metal plate 18 is inserted upto the left stopper 6.
Successively, as illustrated in FIG. 2, the right clamp 4 is lowered to fix the right metal plate 18, and the right stopper 8 is pushed by the right cylinder 12 to advance.
At this time, advanced distance of the right stopper 8 is adjusted by adjustment of an adjuster 16 mounted at a rear side of the right cylinder 12. Then, the left clamp 2 is raised to insert a left metal plate 20 thereunder. The left metal plate 20 is pushed upto the right stopper 8.
At next stage, as illustrated in FIG. 3, the left clamp 2 is lowered to fix the left metal plate 20. A welding part where the left and right metal plates 20 and 18 are lapped is advanced by roll electrode 22 for welding.
However, there is a problem in the welding positioning system thus described according to the prior art in that many steps are involved in determining the welding positions of the metal plates to thereby lengthening the position determining time.
There is another problem in that each adjuster should be individually adjusted in order to adjust the degree of lapped portion because the degree of lapped portion should be adjusted according to thickness of the metal plate, thereby taking a lot of working hours. There is still another problem in that the degree of lapped portion is varied according to individual adjustment of each adjuster, resulting in disaccorded center line of welding and generation of bad welding.
The present invention is disclosed to solve the aforementioned problems and it is one object of the present invention to provide a welding positioning system for seam welding adapted to simplify a positioning determination of welding portion, thereby reducing working hours for taking the positioning determination.
It is another object of the present invention to provide a welding positioning system for seam welding adapted to automatically adjust the degree of lapped portion according to thickness of metal plate, thereby reducing adjusting time.
It is still another object of the present invention to provide a welding positioning system for seam welding adapted to automatically accord the center line of welding, thereby improving a welded quality.
In accordance with the objects of the present invention, there is provided a welding positioning system for seam welding, the system comprising:
a stopper vertically moving according to the center line of welding to adjust the degree of lapped portion at left and right metal plates;
left and right hinge brackets rotatably mounted at a hinge axis at one side thereof in order to rotate within a predetermined range the metal plates inserted into the left and right sides of the stopper; and
a pair of left and right clamps mounted at one side of the left and right hinge brackets for moving vertically to fix the metal plates.